1. Division of Emergency Medicine, University of Cape Town, Cape Town, South Africa
2. Division of Emergency Medicine, Stellenbosch University, Stellenbosch, South Africa
3. Naval Medical Research Unit-San Antonio, Fort Sam Houston, San Antonio, Texas, USA
4. Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
5. University of California, San Francisco, CA, USA